waqtc book

EMBANKMENT AND BASE WAQTC APPENDIX A IN-PLACE DENSITY

Table of Contents

FIELD OPERATING PROCEDURES - SHORT FORM

Chapter Section 1 AASHTO T 255

Total Evaporable Moisture Content of Aggregate by Drying; and AASHTO T 265

Laboratory Determination of Moisture Content of Soils

2 AASHTO T 99 Moisture-Density Relations of Soils Using a 2.5-kg (5.5-lb) Rammer and 305-mm (12-in.) Drop; AASHTO T 180 Moisture-Density Relations of Soils Using a 4.54-kg (10-lb) Rammer and 457-mm (18-in.) Drop

3 AASHTO 272

Family of Curves One-Point Method

4 AASHTO T 85 Specific Gravity and Absorption of Coarse Aggregate

5 AASHTO T 224 Correction for Coarse Particles in the Soil Compaction Test

6 AASHTO T 310 In-Place Density and Moisture Content of Soil and Soil-Aggregate by the

Nuclear Method

EMBANKMENT AND BASE WAQTC AASHTO T 255/T 265 (14) IN-PLACE DENSITY

T255_T265_short_14 E&B/ID 13-1 Pub. October 2014

TOTAL EVAPORABLE MOISTURE CONTENT OF AGGREGATE BY DRYING FOP FOR AASHTO T 255 LABORATORY DETERMINATION OF MOISTURE CONTENT OF SOILS FOP FOR AASHTO T 265 Scope This procedure covers the determination of moisture content of aggregate and soil in accordance with AASHTO T 255-00 and AASHTO T 265-12. It may also be used for other construction materials. Overview Moisture content is determined by comparing the wet mass of a sample and the mass of the sample after drying to constant mass. The term constant mass is used to define when a sample is dry. Constant mass the state at which a mass does not change more than a given percent, after additional drying for a defined time interval, at a required temperature. Apparatus Balance or scale: capacity sufficient for the principle sample mass, accurate to 0.1

percent of sample mass or readable to 0.1 g, and meeting the requirements of AASHTO M 231

Containers, clean, dry and capable of being sealed Suitable drying containers Microwave safe container with ventilated lid Heat source, controlled:

Forced draft oven

Ventilated oven Convection oven

Heat source, uncontrolled:

Infrared heater/heat lamp, hot plate, fry pan, or any other device/method that will dry the sample without altering the material being dried

Microwave oven (900 watts minimum)



Utensils such as spoons Hot pads or gloves Sample Preparation In accordance with the FOP for AASHTO T 2 obtain a representative sample in its existing condition. For aggregates the representative sample size is based on Table 1 or other information that may be specified by the agency.

TABLE 1 Sample Sizes for Moisture Content of Aggregate Nominal Maximum

Size* mm (in.)

Minimum Sample Mass g (lb)

4.75 (No. 4) 500 (1.1) 9.5 (3/8) 1500 (3.3)

12.5 (1/2) 2000 (4) 19.0 (3/4) 3000 (7) 25.0 (1) 4000 (9) 37.5 (1 1/2) 6000 (13)

50 (2) 8000 (18) 63 (2 1/2) 10,000 (22) 75 (3) 13,000 (29) 90 (3 1/2) 16,000 (35)

100 (4) 25,000 (55) 150 (6) 50,000 (110)

* One sieve larger than the first sieve to retain more than 10 percent of the material using an agency specified set of sieves based on cumulative percent retained. Where large gaps in specification sieves exist, intermediate sieve(s) may be inserted to determine nominal maximum.



For soils the representative sample size is based on Table 2 or other information that may be specified by the agency.

TABLE 2 Sample Sizes for Moisture Content of Soil

Maximum Particle

Size mm (in)

Minimum Sample Mass g

0.425 (No. 40) 10 4.75 (No. 4) 100 12.5 (1/2) 300 25.0 (1) 500 50 (2) 1000

Immediately seal or cover samples to prevent any change in moisture content or follow the steps in Procedure. Procedure Determine and record the sample mass as follows:

For aggregate, determine and record all masses to the nearest 0.1 percent of the sample mass or to the nearest 0.1 g.

For soil, determine and record all masses to the nearest 0.1 g.

When determining the mass of hot samples or containers or both, place and tare a buffer between the sample container and the balance. This will eliminate damage to or interference with the operation of the balance or scale. 1. Determine and record the mass of the container (and lid for microwave drying).

2. Place the wet sample in the container.

a. For oven(s), hot plates, infrared heaters, etc.: Spread the sample in the container. b. For microwave oven: Heap sample in the container; cover with ventilated lid.

3. Determine and record the total mass of the container and wet sample. 4. Determine and record the wet mass of the sample by subtracting the container mass

determined in Step 1 from the mass of the container and sample determined in Step 3.



5. Place the sample in one of the following drying apparatus:

a. For aggregate

i. Controlled heat source (oven): at 110 5C (230 9F).

ii. Uncontrolled heat source (Hot plate, infrared heater, etc.): Stir frequently to avoid localized overheating.

b. For soil controlled heat source (oven): at 110 5C (230 9F).

Note 1: Soils containing gypsum or significant amounts of organic material require special drying. For reliable moisture contents dry these soils at 60C (140F). For more information see AASHTO T 265, Note 2.

6. Dry until sample appears moisture free. 7. Determine mass of sample and container. 8. Determine and record the mass of the sample by subtracting the container mass

determined in Step 1 from the mass of the container and sample determined in Step 7. 9. Return sample and container to the heat source for additional drying.

a. For aggregate

i. Controlled heat source (oven): 30 minutes

ii. Uncontrolled heat source (Hot plate, infrared heater, etc.): 10 minutes

iii. Uncontrolled heat source (Microwave oven): 2 minutes

Caution: Some minerals in the sample may cause the aggregate to overheat, altering the aggregate gradation.

b. For soil controlled heat source (oven): 1 hour

10. Determine mass of sample and container. 11. Determine and record the mass of the sample by subtracting the container mass


12. Determine percent change by subtracting the new mass determination (Mn) from the

previous mass determination (Mp) divide by the previous mass determination (Mp) multiply by 100.



13. Continue drying, performing steps 9 through 12, until there is:

a. For Aggregate less than a 0.10 percent change after additional drying time.

b. For Soil no change after additional drying time. A sample dried overnight (15 to

16 hours) is sufficient in most cases.

14. Constant mass has been achieved, sample is defined as dry. 15. Allow the sample to cool. Immediately determine and record the total mass of the

container and dry sample. 16. Determine and record the dry mass of the sample by subtracting the mass of the container


17. Determine and record percent moisture by subtracting the final dry mass determination (MD) from the initial wet mass determination (MW) divide by the final dry mass determination (MD) multiply by 100.

Table 3 Methods of Drying

Aggregate

Heat Source Specific Instructions Drying intervals to

achieve constant mass (minutes)

Controlled: Forced draft (preferred), ventilated, or convection oven

110 5C (230 9F) 30

Uncontrolled:Hot plate, infrared heater, etc. Stir frequently 10

Microwave Heap sample and cover

with ventilated lid 2

Soil

Heat Source Specific Instructions Drying increments (minutes)Controlled: Forced draft (preferred), ventilated, or convection oven

110 5C (230 9F) 1 hour



Calculation

Constant Mass:

Calculate constant mass using the following formula:

100 %Change

Where: Mp = previous mass measurement

Mn = new mass measurement Example: Mass of container: 1232.1 g

Mass of container and sample after first drying cycle: 2637.2 g

Mass, Mp, of possibly dry sample: 2637.2 g - 1232.1 g = 1405.1 g

Mass of container and dry sample after second drying cycle: 2634.1 g

Mass, Mn, of dry sample: 2634.1 g - 1232.1 g = 1402.0 g

1405.1 1402.01405.1 100 0.22%

0.22 percent is not less than 0.10 percent, so continue drying

Mass of container and dry sample after third drying cycle: 2633.0 g Mass, Mn, of dry sample: 2633.0 g - 1232.1 g = 1400.9 g

1402.0 1400.91402.0 100 0.08%

0.08 percent is less than 0.10 percent, so constant mass has been reached for an aggregate, but continue drying for soil.



Moisture Content: Calculate the moisture content, as a percent, using the following formula:

100

Where: w = moisture content, percent

MW = wet mass

MD = dry mass

Example:

Mass of container: 1232.1 g

Mass of container and wet sample: 2764.7 g

Mass, MW, of wet sample: 2764.7 g - 1232.1 g = 1532.6 g

Mass of container and dry sample (COOLED): 2633.0 g

Mass, MD, of dry sample: 2633.0 g - 1232.1 g = 1400.9 g

1532.6 1400.91400.9 100 131.71400.9 100 9.40%9.4%

Report Results on forms approved by the agency MW, wet mass MD, dry mass w, moisture content to nearest 0.1 percent

EMBANKMENT AND BASE WAQTC AASHTO T 255/T 265 REVIEW IN-PLACE DENSITY

T255_T265_rev_10 E&B/ID 3-9 Pub. October 2012

REVIEW QUESTIONS

1. What extra care should be taken when using a microwave to dry aggregates?

2. What is the maximum temperature that a sample should be allowed to attain for each of the various types of ovens?

3. How is constant mass defined according to this FOP:

For Aggregate?

For Soil?

EMBANKMENT AND BASE WAQTC AASHTO T 255/T 265 REVIEW IN-PLACE DENSITY


EMBANKMENT AND BASE WAQTC AASHTO T 255/T265 REVIEW IN-PLACE DENSITY

T255_T265_rev E&B/ID 3-9 October 2012

REVIEW QUESTION ANSWERS

1. What extra care should be taken when using a microwave to dry aggregates?

Microwave safe containers.

2. What are the maximum temperatures that a sample should be allowed to attain when using the various types of ovens?

239 F

3. How is constant mass defined according to this FOP:

For Aggregate?

Less than a 0.10% change after an additional: 30 minutes of drying in an oven

10 minutes of drying in a microwave 20 minutes of drying using other means

For Soil?

No change after an additional hour of drying.

EMBANKMENT AND BASE WAQTC FOP AASHTO T 99/T 180 (14) IN-PLACE DENSITY


MOISTURE-DENSITY RELATIONS OF SOILS: USING A 2.5 kg (5.5 lb) RAMMER AND A 305 mm (12 in.) DROP FOP FOR AASHTO T 99 USING A 4.54 kg (10 lb) RAMMER AND A 457 mm (18 in.) DROP FOP FOR AASHTO T 180 Scope This procedure covers the determination of the moisture-density relations of soils and soil-aggregate mixtures in accordance with two similar test methods:

AASHTO T 99-10: Methods A, B, C, and D

AASHTO T 180-10: Methods A, B, C, and D This test method applies to soil mixtures having 40% or less retained on the 4.75 mm (No 4) sieve for methods A or B, or, 30% or less retained on the 19 mm () with methods C or D. The retained material is defined as oversize (coarse) material. If no minimum percentage is specified, 5% will be used. Samples that contain oversize (coarse) material that meet percent retained criteria should be corrected by using the FOP for AASHTO T 224. Samples of soil or soil-aggregate mixture are prepared at several moisture contents and compacted into molds of specified size, using manual or mechanical rammers that deliver a specified quantity of compactive energy. The moist masses of the compacted samples are multiplied by the appropriate factor to determine moist density values. Moisture contents of the compacted samples are determined and used to obtain the dry density values of the same samples. Maximum dry density and optimum moisture content for the soil or soil-aggregate mixture is determined by plotting the relationship between dry density and moisture content. Apparatus

Mold Cylindrical, made of metal and with the dimensions shown in Table 1 or Table 2. It shall include a detachable collar and a base plate to which the mold can be fastened. If permitted by the agency, the mold may be of the split type, consisting of two half-round sections, which can be securely locked in place to form a cylinder.

Rammer Manually or mechanically-operated rammers as detailed in Table 1 or

Table 2. A manually-operated rammer shall be equipped with a guide sleeve to control the path and height of drop. The guide sleeve shall have at least four vent holes no smaller than 9.5 mm (3/8 in.) in diameter, spaced approximately 90 degrees apart and approximately 19 mm (3/4 in.) from each end. A mechanically-operated rammer will uniformly distribute blows over the sample and will be calibrated with several soil types, and be adjusted, if necessary, to give the same moisture-density results as with the manually operated rammer. For additional information concerning calibration, see the FOP for AASHTO T 99 and T 180.

Sample extruder A jack, lever frame, or other device for extruding compacted

specimens from the mold quickly and with little disturbance.



Balance(s) or scale(s) of the capacity and sensitivity required for the procedure used by the agency.

A balance or scale with a capacity of 20 kg (45 lb) and a sensitivity of 5 g (0.01 lb) for obtaining the sample, meeting the requirements of AASHTO M 231. A balance or scale with a capacity of 2 kg and a sensitivity of 0.1 g is used for moisture content determinations done under both procedures, meeting the requirements of AASHTO M 231.

Drying apparatus A thermostatically controlled drying oven, capable of maintaining

a temperature of 110 5C (230 9F) for drying moisture content samples in accordance with the FOP for AASHTO T 255/T 265.

Straightedge A steel straightedge at least 250 mm (10 in.) long, with one beveled

edge and at least one surface plane within 0.1 percent of its length, used for final trimming.

Sieve(s) 4.75 mm (No. 4) and/or 19.0 mm (3/4 in.), conforming to AASHTO M 92.

Mixing tools Miscellaneous tools such as a mixing pan, spoon, trowel, spatula, etc.,

or a suitable mechanical device, for mixing the sample with water.

Containers with close-fitting lids to prevent gain or loss of moisture in the sample.

Table 1 Comparison of Apparatus, Sample, and Procedure Metric

T 99 T 180 Mold Volume, m3 Methods A, C: 0.000943

0.000008 Methods A, C: 0.000943 0.000008

Methods B, D: 0.002124 0.000021

Methods B, D: 0.002124 0.000021

Mold Diameter, mm Methods A, C: 101.6 0.41 Methods A, C: 101.6 0.41 Methods B, D: 152.4 2.54 Methods B, D: 152.4 2.54

Mold Height, mm 116.43 0.13 116.43 0.13 Detachable Collar Height, mm 50.80 0.64 50.80 0.64 Rammer Diameter, mm 50.80 50.80 Rammer Mass, kg 2.495 4.536 Rammer Drop, mm 305 457 Layers 3 5 Blows per Layer Methods A, C: 25 Methods A, C: 25

Methods B, D: 56 Methods B, D: 56 Material Size, mm Methods A, B: 4.75 minus Methods A, B: 4.75 minus

Methods C, D: 19.0 minus Methods C, D: 19.0 minus Test Sample Size, kg Method A: 3 Method B: 7

Method C: 5 (1) Method D: 11(1)

Energy, kN-m/m3 592 2,693 (1) This may not be a large enough sample depending on your nominal maximum size for moisture content samples.



Table 2 Comparison of Apparatus, Sample, and Procedure English

T 99 T 180 Mold Volume, ft3 Methods A, C: 1/30

(0.0333) 0.0003 Methods A, C: 1/30 (0.0333) 0.0003

Methods B, D: 1/13.33 (0.0750) 0.00075

Methods B, D: 1/13.33 (0.0750) 0.00075

Mold Diameter, in. Methods A, C: 4.0000.016 Methods A, C: 4.0000.016 Methods B, D: 6.000 0.100 Methods B, D: 6.000 0.100

Mold Height, in. 4.584 0.005 4.584 0.005 Detachable Collar Height, in. 2 0.025 2 0.025 Rammer Diameter, in. 2.000 0.025 2.000 0.025 Rammer Mass, lb 5.5 0.02 10 0.02 Rammer Drop, in. 12 18 Layers 3 5 Blows per Layer Methods A, C: 25 Methods A, C: 25

Methods B, D: 56 Methods B, D: 56 Material Size, in. Methods A, B: No. 4 minus Methods A, B: No.4 minus

Methods C, D: 3/4 minus Methods C, D: 3/4 minus Test Sample Size, lb Method A: 7 Method B: 16

Method C: 12(1) Method D: 25(1)

Energy, lb-ft/ft3 12,375 56,250 (1) This may not be a large enough sample depending on your nominal maximum size for moisture content samples.

Molds Out of Tolerance Due to UseA mold that fails to meet manufacturing tolerances after continued service may remain in use provided those tolerances are not exceeded by more than 50 percent; and the volume of the mold, calibrated in accordance with T 19M/T 19, is used in the calculations.

Sample If the sample is damp, dry it until it becomes friable under a trowel. Drying may be in air or by use of a drying apparatus maintained at a temperature not exceeding 60C (140F). Thoroughly break up aggregations in a manner that avoids reducing the natural size of individual particles. Obtain a representative test sample of the mass required by the agency by passing the material through the sieve required by the agency. See Table 1 or Table 2 for test sample mass and material size requirements.

Note 1: Both T 99 and T 180 have four methods (A, B, C, D) that require different masses and employ different sieves.

Note 2: If the sample is plastic (clay types), it should stand for a minimum of 12 hours after the addition of water to allow the moisture to be absorbed. In this case, several samples at different moisture contents should be prepared, put in sealed containers and tested the next day. In instances where the material is prone to degradation, i.e., granular material, a compaction sample with differing moisture contents should be prepared for each point.



Procedure During compaction, the mold shall rest firmly on a dense, uniform, rigid, and stable foundation or base. This base shall remain stationary during the compaction process. 1. Determine the mass of the clean, dry mold. Include the base plate, but exclude the

extension collar. Record the mass to the nearest 0.005 kg (0.01 lb). 2. Thoroughly mix the selected representative sample with sufficient water to dampen it to

approximately 4 to 8 percentage points below optimum moisture content. See Note 2. For many materials this condition can be identified by forming a cast by hand.

3. Form a specimen by compacting the prepared soil in the mold (with collar attached) in

approximately equal layers. For each layer:

a. Spread the loose material uniformly in the mold. Note 3: It is recommended to cover the remaining material with a non-absorbent sheet or damp cloth to

minimize loss of moisture.

b. Lightly tamp the loose material with the manual rammer or other similar device, this establishes a firm surface.

c. Compact each layer with uniformly distributed blows from the rammer. See Table 1

for mold size, number of layers, number of blows, and rammer specification for the various test methods. Use the method specified by the agency.

d. Trim down material that has not been compacted and remains adjacent to the walls of

the mold and extends above the compacted surface.

4. Remove the extension collar. Avoid shearing off the sample below the top of the mold. A rule of thumb is that the material compacted in the mold should not be over 6 mm ( in.) above the top of the mold once the collar has been removed.

5. Trim the compacted soil even with the top of the mold with the beveled side of the

straightedge. 6. Determine the mass of the mold and wet soil to the nearest 0.005 kg (0.01 lb) or better. 7. Determine the wet mass of the sample by subtracting the mass in Step 1 from the mass in

Step 6. 8. Calculate the wet density as indicated below under Calculations. 9. Extrude the material from the mold. For soils and soil-aggregate mixtures, slice vertically

through the center and take a representative moisture content sample from one of the cut faces, ensuring that all layers are represented. For granular materials, a vertical face will



not exist. Take a representative sample. This sample must meet the sample size requirements of the test method used to determine moisture content.

Note 4: When developing a curve for free-draining soils such as uniform sands and gravels, where seepage occurs at the bottom of the mold and base plate, taking a representative moisture content from the mixing bowl may be preferred in order to determine the amount of moisture available for compaction.

10. Determine the moisture content of the sample in accordance with the FOP for AASHTO T 255 / T 265.

11. Thoroughly break up the remaining portion of the molded specimen until it will again

pass through the sieve, as judged by eye, and add to the remaining portion of the sample being tested. See Note 2.

12. Add sufficient water to increase the moisture content of the remaining soil by approximately 1 to 2 percentage points and repeat steps 3 through 11.

13. Continue determinations until there is either a decrease or no change in the wet density.

There will be a minimum of three points on the dry side of the curve and two points on the wet side.

Note 5: In cases of free-draining granular material, the development of points on the wet side of optimum may not be practical.

Calculations When the mold meets the criteria of Table 1 or Table 2 calculating unit mass can be accomplished by multiplication using a Mold Factor, by division using a Mold volume; or by division using a measured volume (determined by performing AASHTO T 19). For molds not meeting the criteria of Table 1 or Table 2 but within 50%, a measured volume must be used. Mold Factor 1a. Calculate the wet density, in kg/m3 (lb/ft3), by multiplying the wet mass from Step 7

by the appropriate factor chosen from the two below.

Methods A and C molds: 1060 (30) Methods B and D molds: 471 (13.33)

Note 6: The moist mass is in kg (lb). The factors are the inverses of the mold volumes in m3 (ft3) shown in Table 1 or Table 2. If the moist mass is in grams, use 1.060 or 0.471 for factors when computing kg/m3.

Example Methods A or C mold: Wet mass = 1.916 kg (4.22 lb) (1.916)(1060) = 2031 kg/m3 Wet Density* (4.22)(30) = 126.6 lb/ft3 Wet Density*



Volume 1b. Calculate the wet density, in kg/m3 (lb/ft3), by dividing the wet mass from Step 7 by

the appropriate volume from Table 1 or Table 2.

Example Methods A or C mold: Wet mass = 1.916 kg (4.22 lb)

1.1916

0.000943 2023 4.220.0333 126.7

* Differences in wet density are due to rounding in the respective calculations.

Measured Volume 1c. Calculate the wet density, in kg/m3 (lb/ft3), by dividing the wet mass by the measured

volume of the mold (T 19).

Example Methods A or C mold: Wet mass = 1.916 kg (4.22 lb) Measured volume of the mold = 0.000946m3 (0.0334 ft3)

1.19160.000946 2025

4.220.0334 126.3

2. Calculate the dry density as follows.

100 100

100 1

Where:

d = Dry density, kg/m3 (lb/ft3) w = Wet density, kg/m3 (lb/ft3) w = Moisture content, as a percentage

39



Example: w = 2030 kg/m3 (126.6 lb/ft3) and w = 14.7%

2030

14.7 100 100 1770 126.6

14.7 100 100 110.4

or

2030

14.7100 1

1770 126.6

14.7100 1

110.4

Moisture-Density Curve Development When dry density is plotted on the vertical axis versus moisture content on the horizontal axis and the points are connected with a smooth line, a moisture-density curve is developed. The coordinates of the peak of the curve are the maximum dry density, or just maximum density, and the optimum moisture content of the soil. Example: Given the following dry density and corresponding moisture content values develop a moisture-density relations curve and determine maximum dry density and optimum moisture content.

Dry Density kg/m3 lb/ft3

Moisture Content, %

1846 114.3 11.3 1868 115.7 12.1 1887 116.9 12.8 1884 116.7 13.6 1871 115.9 14.2

117 115 113

Dry

den

sity

lb

/ft3



In this case, the curve has its peak at: Maximum dry density = 1890 kg/m3 (117.0 lb/ft3) Optimum water content = 13.2% Note that both values are approximate, since they are based on sketching the curve to fit the points. Report

Results on forms approved by the agency Maximum dry density to the closest 1 kg/m3 (0.1 lb/ft3) Optimum moisture content to the closest 0.1 percent

EMBANKMENT AND BASE WAQTC T 99 / T 180 REVIEW IN-PLACE DENSITY


REVIEW QUESTIONS

1. Describe how the plotted data is used to determine optimum moisture content and maximum dry density.

2. How many blows of the rammer are required per lift for the various procedures and methods?

3. Describe how the sample for moisture content is obtained.

4. What sample mass is required for Method A of the T 99 test?

For Method C of the T 180 test?

EMBANKMENT AND BASE WAQTC T 99 / T 180 REVIEW IN-PLACE DENSITY


EMBANKMENT AND BASE WAQTC T 99_ T 180 REVIEW IN-PLACE DENSITY

T99_T180_rev E&B/ID 5-13 October 2012


1. Describe how the plotted data is used to determine optimum moisture content and maximum dry density.

Dry density is plotted on the vertical axis while the moisture content is plotted on the horizontal axis. The plotted points are then connected, in a smooth curve, to create a moisture-density curve. The peak of the curve is the optimum moisture and maximum dry density for that curve.

2. How many blows of the rammer are required per lift for the various procedures and methods?

Methods A & C = 25 blows per lift. Methods B & D = 56 blows per lift.

3. Describe how the sample for moisture content is obtained.

With the cylinder in an upright position, slice vertically through the center of the cylinder and take a representative sample from all layers represented.

4. What sample mass is required for Method A of the T 99 test?

7 lbs.

For Method C of the T 180 test?

12 lbs.

EMBANKMENT AND BASE WAQTC FOP AASHTO T 272 (12) IN-PLACE DENSITY

T272_short_12 E&B/ID 15-1 Pub. October 2013

FAMILY OF CURVES ONE-POINT METHOD FOP FOR AASHTO T 272 Scope This procedure provides for a rapid determination of the maximum density and optimum moisture content of a soil sample, utilizing a family of curves and a one-point determination in accordance with AASHTO T 272-10. This procedure is related to the FOP for AASHTO T 99/T 180. One-point determinations are made by compacting the soil in a mold of a given size with a specified rammer dropped from a specified height. Four alternate methods A, B, C, and D are used and correspond to the methods described in the FOP for AASHTO T 99/T 180. The method used in AASHTO T 272 must match the method used in the FOP for AASHTO T 99/T 180. Apparatus See the FOP for AASHTO T 99/T 180. Sample Sample size determined according to the FOP for AASHTO T 310. In cases where the existing family cannot be used a completely new curve will need to be developed and the sample size will be determined by the FOP for AASHTO T 99/T 180. Procedure See the FOP for AASHTO T 99/T 180. Calculations See the FOP for AASHTO T 99/T 180. Maximum Dry Density and Optimum Moisture Content Determination 1. If the moisture-density one-point falls on one of the curves in the existing family of

curves, the maximum dry density and optimum moisture content defined by that curve shall be used.

2. If the moisture-density one-point falls within the family of curves but not on an existing

curve, a new curve shall be drawn through the plotted single point, parallel and in character with the nearest existing curve in the family of curves. The maximum dry density and optimum moisture content as defined by the new curve shall be used.



3. The one-point must fall either between or on the highest or lowest curves in the family. If it does not, then a full curve must be developed.

4. If the one-point plotted within or on the family of curves does not fall in the 80 to 100

percent of optimum moisture content, compact another specimen, using the same material, at an adjusted moisture content that will place the one point within this range.

5. If the family of curves is such that the new curve through a one-point is not well defined

or is in any way questionable, a full moisture-density relationship shall be made for the soil to correctly define the new curve and verify the applicability of the family of curves.

Note 1: New curves drawn through plotted single point determinations shall not become a permanent part of the family of curves until verified by a full moisture-density procedure following the FOP for AASHTO T 99/T 180.

EXAMPLE

o



Example A moisture-density procedure (FOP for AASHTO T 99/T 180) was performed. A dry density of 114.4 lb/ft3 and a corresponding moisture content of 11.4 percent were determined. This point was plotted on the appropriate family between two previously developed curves. The dashed curve beginning at the moisture-density one-point was sketched between the two existing curves. A maximum dry density of 117.0 lb/ft3 and a corresponding optimum moisture content of 13.5 percent were estimated. Report

Results on forms approved by the agency Maximum dry density to the closest 1 kg/m3 (0.1 lb/ft3) Optimum moisture content to the closest 0.1 percent

EMBANKMENT AND BASE WAQTC AASHTO T 272 REVIEW IN-PLACE DENSITY

T272_rev_09 E&B/ID 5-5 Pub. October 2012

REVIEW QUESTIONS

1. To what other procedure(s) is this procedure related?

2. How are the two procedures used together?

3. Describe the limitations of using the one-point determination with a family of curves.


T272-rev E&B/ID 6-7 October 2012


1. With what other procedure(s) is this procedure related?

Field Operating Procedure AASHTO T 99 & AASHTO T 180.

2. How are the two procedures used together?

One-point determinations are made using AASHTO T 99 & T 180.

3. Describe the limitations of using the one-point determination with a family of curves?

The plotted point must plot between 80 100% of the family of curves optimum moisture content on the dry side of the curve.

Not well defined or questionable curves should not be used, and a new, full moisture density curve shall be made.



SPECIFIC GRAVITY AND ABSORPTION OF COARSE AGGREGATE FOP FOR AASHTO T 85 Scope This procedure covers the determination of specific gravity and absorption of coarse aggregate in accordance with AASHTO T 85-14. Specific gravity may be expressed as bulk specific gravity (Gsb), bulk specific gravity, saturated surface dry (Gsb SSD), or apparent specific gravity (Gsa). Gsb and absorption are based on aggregate after soaking in water. This procedure is not intended to be used with lightweight aggregates. Terminology Absorption the increase in the mass of aggregate due to water being absorbed into the pores of the material, but not including water adhering to the outside surface of the particles, expressed as a percentage of the dry mass. The aggregate is considered dry when it has been maintained at a temperature of 110 5C (230 9F) for sufficient time to remove all uncombined water. Saturated Surface Dry (SSD) condition of an aggregate particle when the permeable voids are filled with water, but no water is present on exposed surfaces. Specific Gravity the ratio of the mass, in air, of a volume of a material to the mass of the same volume of gas-free distilled water at a stated temperature. Apparent Specific Gravity (Gsa) the ratio of the mass, in air, of a volume of the impermeable portion of aggregate to the mass of an equal volume of gas-free distilled water at a stated temperature. Bulk Specific Gravity (Gsb) the ratio of the mass, in air, of a volume of aggregate (including the permeable and impermeable voids in the particles, but not including the voids between particles) to the mass of an equal volume of gas-free distilled water at a stated temperature. Bulk Specific Gravity (SSD) (Gsb SSD) the ratio of the mass, in air, of a volume of aggregate, including the mass of water within the voids filled to the extent achieved by submerging in water for 15 to 19 hours (but not including the voids between particles), to the mass of an equal volume of gas-free distilled water at a stated temperature. Apparatus

Balance or scale: with a capacity of 5 kg, sensitive to 1 g. Meeting the requirements of AASHTO M 231.



Sample container: a wire basket of 3.35 mm (No. 6) or smaller mesh, with a capacity of 4 to 7 L (1 to 2 gal) to contain aggregate with a nominal maximum size of 37.5 mm (1 1/2 in.) or smaller; or a larger basket for larger aggregates, or both.

Water tank: watertight and large enough to completely immerse aggregate and basket,

equipped with an overflow valve to keep water level constant.

Suspension apparatus: wire used to suspend apparatus shall be of the smallest practical diameter.

Sieves 4.75 mm (No. 4) or other sizes as needed, conforming to AASHTO M 92.

Large absorbent towel

Sample Preparation 1. Obtain the sample in accordance with the FOP for AASHTO T 2 (see Note 1). 2. Mix the sample thoroughly and reduce it to the approximate sample size required by

Table 1 in accordance with the FOP for AASHTO T 248. 3. Reject all material passing the appropriate sieve by dry sieving. 4. Thoroughly wash sample to remove dust or other coatings from the surface and re-screen

the washed dry sample over the appropriate sieve. Reject all material passing that sieve. 5. The sample shall meet or exceed the minimum mass given in Table 1.

Note 1: If this procedure is used only to determine the Bulk Gsb of oversized material for the FOP for AASHTO T 99 / T 180 and in the calculations for the FOP for AASHTO T 224, the material can be rejected over the appropriate sieve. For T 99 / T 180 Methods A and B, use the 4.75 mm (No. 4) sieve; T 99 / T 180 Methods C and D use the 19 mm (3/4 in).

Table 1 Nominal Maximum Size*

mm (in.) Minimum Mass of Test

Sample, g (lb) 12.5 (1/2) or less 2000 (4.4) 19.0 (3/4) 3000 (6.6) 25.0 (1) 4000 (8.8) 37.5 (1 1/2) 5000 (11)

50 (2) 8000 (18) 63 (2 1/2) 12,000 (26) 75 (3) 18,000 (40)

* One sieve larger than the first sieve to retain more than 10 percent of the material using an agency specified set of sieves based on cumulative percent retained. Where large gaps in specification sieves exist, intermediate sieve(s) may be inserted to determine nominal maximum size.



Procedure 1. Dry the test sample to constant mass at a temperature of 110 5C (230 9F) and cool in

air at room temperature for 1 to 3 hours.

Note 2: Where the absorption and specific gravity values are to be used in proportioning concrete mixtures in which the aggregates will be in their naturally moist condition, the requirement for initial drying to constant mass may be eliminated, and, if the surfaces of the particles in the sample have been kept continuously wet until test, the 15-to-19 hour soaking may also be eliminated.

2. Immerse the aggregate in water at room temperature for a period of 15 to 19 hours. Note 3: When testing coarse aggregate of large nominal maximum size requiring large test samples, it may be more convenient to perform the test on two or more subsamples, and then combine the values obtained.

3. Place the empty basket into the water bath and attach to the balance. Inspect the immersion tank to ensure the water level is at the overflow outlet height. Tare the balance with the empty basket attached in the water bath.

4. Remove the test sample from the water and roll it in a large absorbent cloth until all

visible films of water are removed. Wipe the larger particles individually. If the test sample dries past the SSD condition, immerse in water for 30 min, and then resume the process of surface-drying.

Note 4: A moving stream of air may be used to assist in the drying operation, but take care to avoid evaporation of water from aggregate pores.

5. Determine the SSD mass of the sample, and record this and all subsequent masses to the nearest 0.1 g or 0.1 percent of the sample mass, whichever is greater. Designate this mass as B.

6. Immediately place the SSD test sample in the sample container and weigh it in water

maintained at 23.0 1.7C (73.4 3F). Shake the container to release entrapped air before recording the weight. Re-inspect the immersion tank to insure the water level is at the overflow outlet height. Designate this submerged weight as C.

Note 5: The container should be immersed to a depth sufficient to cover it and the test sample during mass determination. Wire suspending the container should be of the smallest practical size to minimize any possible effects of a variable immersed length.

7. Remove the sample from the basket. Ensure all material has been removed. Place in a container of known mass.

8. Dry the test sample to constant mass in accordance with the FOP for AASHTO T 255 /

T 265 (Aggregate section) and cool in air at room temperature for 1 to 3 hours. Designate this mass as A.



Calculations Perform calculations and determine values using the appropriate formula below. In these formulas, A = oven dry mass, B = SSD mass, and C = weight in water. Bulk specific gravity (Gsb)

Bulk specific gravity, SSD (Gsb SSD)

Apparent specific gravity (Gsa)

Absorption

Absorption 100 Sample Calculations

Sample A B C B - C A - C B - A 1 2030.9 2044.9 1304.3 740.6 726.6 14.0 2 1820.0 1832.5 1168.1 664.4 651.9 12.5 3 2035.2 2049.4 1303.9 745.5 731.3 14.2

Sample Gsb Gsb SSD Gsa Absorption 1 2.742 2.761 2.795 0.7 2 2.739 2.758 2.792 0.7 3 2.730 2.749 2.783 0.7

These calculations demonstrate the relationship between Gsb, Gsb SSD, and Gsa. Gsb is always lowest, since the volume includes voids permeable to water. Gsb SSD is always intermediate. Gsa is always highest, since the volume does not include voids permeable to water. When running this test, check to make sure the values calculated make sense in relation to one another.



Report Results on forms approved by the agency Specific gravity values to 3 decimal places Absorption to 0.1 percent .



REVIEW QUESTIONS

1. What size sample is required for aggregate with a nominal maximum size of 25 mm (1 in.)?

2. When is soaking required? For how long must material be soaked?

3. When, in the process, are dry and SSD masses determined?

EMBANKMENT AND BASE WAQTC AASHTO T85 REVIEW IN-PLACE DENSITY

T85_rev E&B/ID 7-9 October 2012


1. What size sample is required for aggregate with a nominal maximum size of 25 mm (1 in.)?

9 lbs.

2. When is soaking required? For how long must material be soaked?

When material has not been in a naturally moist condition for the previous 15-19 hrs. or in a continuously watered stockpile for the previous 15-19 hrs.

15 to 19 hours.

3. When, in the process, are dry and SSD masses determined?

Dry masses are determined at the end of the procedure.

SSD mass is the first mass determined.



CORRECTION FOR COARSE PARTICLES IN THE SOIL COMPACTION TEST FOP FOR AASHTO T 224 Scope This procedure covers the adjustment of the maximum dry density determined by FOP for AASHTO T 99 / T 180 to compensate for coarse particles retained on the 4.75 mm (No. 4) or 19.0 mm (3/4 in.) sieve. For Methods A and B of the FOP for AASHTO T 99 / T 180 the adjustment is based on the percent, by mass, of material retained on the 4.75 mm (No. 4) sieve and the bulk specific gravity (Gsb) of the material retained on the 4.75 mm (No. 4) sieve. A maximum of 40 percent of the material can be retained on the 4.75 mm (No. 4) sieve for this method to be used. For Methods C and D of the FOP for AASHTO T 99 / T 180, the adjustment is based on the percent, by mass, of material retained on the 19.0 mm (3/4 in.) sieve and the bulk specific gravity (Gsb) of the material retained on the 19.0 mm (3/4 in.) sieve. A maximum of 30 percent of the material can be retained on the 19.0 mm (3/4 in.) sieve for this method to be used. Whether the split is on the 4.75 mm (No. 4) or the 19.0 mm (3/4 in.) sieve, all material retained on that sieve is defined as oversized material. This method applies to soils with percentages up to the maximums listed above for oversize particles. A correction may not be practical for soils with only a small percentage of oversize material. The agency shall specify a minimum percentage below which the method is not needed. If not specified, this method applies when more than 5 percent by weight of oversize particles is present. This procedure covers the lab-to-field corrections in accordance with AASHTO T 224-10 (see AASHTO T 224 for field-to-lab corrections). Adjustment Equation Moisture Along with density, the moisture content can be corrected. The moisture content can be determined by the FOP for AASHTO T 255 / T 265, other agency approved methods, or the nuclear density gauge moisture content reading from the FOP for AASHTO T 310. If the nuclear gauge moisture reading is used, or when the moisture content is determined on the entire sample (both fine and oversized particles), the use of the adjustment equation is not needed. Combined moisture contents with material having an appreciable amount of silt or clay should be performed using FOP for AASHTO T 255 / T 265 (Soil). Moisture contents used from FOP for AASHTO T 310 must meet the criteria for that method. When samples are split for moisture content (oversized and fine materials) the following adjustment equations must be followed: 1. Split the sample into oversized material and fine material. 2. Dry the oversized material following the FOP for AASHTO T 255 / T 265 (Aggregate).

If the fine material is sandy in nature, dry using the FOP for AASHTO T 255 / T 265 (Aggregate), or other agency approved methods. If the fine material has any appreciable



amount of clay, dry using the FOP for AASHTO T 255 / T 265 (Soil) or other agency approved methods.

3. Calculate the dry mass of the oversize and fine material as follows:

1 MC Where:

MD = mass of dry material (fine or oversize particles). Mm = mass of moist material (fine or oversize particles). MC = moisture content of respective fine or oversized, expressed as a decimal.

4. Calculate the percentage of the fine and oversized particles by dry weight of the total sample as follows: See Note 2.

100 100 15.415.4 5.7 73%

100 7.0347.03 2.602 73%

And

100 100 5.7

15.4 5.7 27%100 2.602

7.03 2.602 27% Or for Pc:

100 Where: Pf = percent of fine particles, of sieve used, by weight. Pc = percent of oversize particles, of sieve used, by weight. MDF = mass of fine particles. MDC = mass of oversize particles.



5. Calculate the corrected moisture content as follows:

100 10.6% 73.0% 2.1% 27.0%

100 8.3% MCT = corrected moisture content of combined fines and oversized particles, expressed as a % moisture. MCF = moisture content of fine particles, as a % moisture. MCC = moisture content of oversized particles, as a % moisture.

Note 1: Moisture content of oversize material can be assumed to be two (2) percent for most construction applications.

Note 2: In some field applications agencies will allow the percentages of oversize and fine materials to be determined with the materials in the wet state.

Adjustment Equation Density 6. Calculate the corrected dry density of the total sample (combined fine and oversized

particles) as follows:

100 100

Where:

Dd = corrected total dry density (combined fine and oversized particles) kg/m3 (lb/ft 3)

Df = dry density of the fine particles kg/m3 (lb/ft3), determined in the lab

Pc= percent of oversize particles, of sieve used, by weight.

Pf = percent of fine particles, of sieve used, by weight.

k = Metric: 1,000 * Bulk Specific Gravity (Gsb) (oven dry basis) of coarse particles (kg/m3).

k = English: 62.4 * Bulk Specific Gravity (Gsb) (oven dry basis) of coarse particles (lb/ft3)



Note 3: If the specific gravity is known, then this value will be used in the calculation. For most construction activities the specific gravity for aggregate may be assumed to be 2.600.

Calculation Sample Calculations: Metric:

Maximum laboratory dry density (Df): 2329 kg/m3

Percent coarse particles (Pc): 27%

Percent fine particles (Pf): 73%

Mass per volume coarse particles (k): (2.697) (1000) = 2697 kg/m3

100 100

100 2329 2697

2329 27% 2697 73%

10073%2329

27%2697

628,131,300

628,883 2697

1000.03134 0.01001

2418.1 2418

2418.1 2418



English:

Maximum laboratory dry density (Df): 140.4 lb/ft3

Percent coarse particles (Pc): 27%

Percent fine particles (Pf): 73%

Mass per volume of coarse particles (k): (2.697) (62.4) = 168.3 lb/ft3

100 100

100 140.4 168.3

140.4 27% 168.3 73%

10073%140.4

27%168.3

2,362,932

3790.8 12285.9 100

0.51994 0.16043

2,362,932

16,076.7 100

0.68037

146.98 147.0 Report Results on forms approved by the agency Adjusted maximum dry density to the closest 1 kg/m3 (0.1 lb/ft3) Adjusted optimum moisture to the 0.1 percent

EMBANKMENT AND BASE WAQTC AASHTO T 224 REVIEW (12) IN-PLACE DENSITY


REVIEW QUESTIONS

1. Describe the purpose of this procedure.

2. The adjustment is based on the mass of material retained on what size sieve?

3. What effect does increased coarse particles have on moisture content?

4. The fine particles in a soil-aggregate mixture have a dry density of 138.6 lb/ft3 English units and a moisture content of 6.4 percent. The coarse particles make up 22 percent of the material, having a Gsb of 2.631 and 1.7 percent moisture.

What is the corrected maximum density?

What is the corrected moisture?

EMBANKMENT AND BASE WAQTC AASHTO T 224 REVIEW (12) IN-PLACE DENSITY





1. Describe the purpose of this procedure.

To adjust the maximum dry density as determined by AASHTO T 99 or 180.

2. The adjustment is based on the mass of material retained on what size sieve?

To compensate for coarse particles retained on the No. 4 or 3/4 inch sieve.

3. What effect does an increase in the percent of coarse particles have on moisture content?

The dry density will increase while the moisture content will decrease.

4. A soil-aggregate mixture has a maximum dry density of fine particles of 138.6 lb/ft3 and a moisture content of 6.4%. The coarse particles make up 22 percent of the material, and have a Gsb of 2.631 at a moisture content of 1.7%.

What is the corrected maximum dry density?

CALCULATION

Dd = ____100 Df k______ [(Df)(Pc) + (k)(Pf)]

Where: Dd = corrected total dry density Given: Df = dry density of the fine particles Df = 138.6 lbs/ft Pc = percent of oversized particles Pc = 22% Pf = percent of fine particles Gsb = 2.631 k = Gsb *(62.4 lbs/ft) MCF = 6.4%

MCC = 1.7%

SOLUTION

Pf = 100 Pc = 100 22 = 78% k = 62.4 lbs/ft x 2.631 = 164.17 lbs/ft = 164.2 lbs/ft

Dd = _(100)(138.6)(164.2)___ = ___2,275,812______ = 2,275,812 = 143.5 lbs/ft (138.6)(22) + (164.2)(78) (3,049.2) + (12,807.6) 15,856.8



What is the corrected moisture?

CALCULATION

MCT = [(MCF x Pf) + (MCC x PC)]/ 100

Where: MCT = Corrected Moisture Content MCF = Moisture content of fines MCC = Moisture content of coarse

SOLUTION

MCT = [(6.4 x 78) + (1.7 x 22)]/ 100

= [499.2 + 37.4]/100

= [536.6]/100

= 5.4%

EMBANKMENT AND BASE WAQTC AASHTO T 310 (13) IN-PLACE DENSITY


IN-PLACE DENSITY AND MOISTURE CONTENT OF SOIL AND SOIL-AGGREGATE BY NUCLEAR METHODS (SHALLOW DEPTH) FOP FOR AASHTO T 310 Scope This procedure covers the determination of density, moisture content, and relative compaction of soil, aggregate, and soil-aggregate mixes in accordance with AASHTO T 310-13. This field operating procedure is derived from AASHTO T 310. The nuclear moisture-density gauge is used in the direct transmission mode. Apparatus

Nuclear density gauge with the factory matched standard reference block.

Drive pin, guide/scraper plate, and hammer for testing in direct transmission mode.

Transport case for properly shipping and housing the gauge and tools.

Instruction manual for the specific make and model of gauge.

Radioactive materials information and calibration packet containing:

Daily Standard Count Log. Factory and Laboratory Calibration Data Sheet. Leak Test Certificate. Shippers Declaration for Dangerous Goods. Procedure Memo for Storing, Transporting and Handling Nuclear Testing

Equipment. Other radioactive materials documentation as required by local regulatory

requirements.

Sealable containers and utensils for moisture content determinations. Radiation Safety This method does not purport to address all of the safety problems associated with its use. This test method involves potentially hazardous materials. The gauge utilizes radioactive materials that may be hazardous to the health of the user unless proper precautions are taken. Users of this gauge must become familiar with the applicable safety procedures and governmental regulations. All operators will be trained in radiation safety prior to operating



nuclear density gauges. Some agencies require the use of personal monitoring devices such as a thermoluminescent dosimeter or film badge. Effective instructions together with routine safety procedures such as source leak tests, recording and evaluation of personal monitoring device data, etc., are a recommended part of the operation and storage of this gauge. Calibration Calibrate the nuclear gauge as required by the agency. This calibration may be performed by the agency using manufacturers recommended procedures or by other facilities approved by the agency. Verify or re-establish calibration curves, tables, or equivalent coefficients every 12 months. Standardization

1. Turn the gauge on and allow it to stabilize (approximately 10 to 20 minutes) prior to standardization. Leave the power on during the days testing.

2. Standardize the nuclear gauge at the construction site at the start of each days work

and as often as deemed necessary by the operator or agency. Daily variations in standard count shall not exceed the daily variations established by the manufacturer of the gauge. If the daily variations are exceeded after repeating the standardization procedure, the gauge should be repaired and/or recalibrated.

3. Record the standard count for both density and moisture in the Daily Standard Count

Log. The exact procedure for standard count is listed in the manufacturers Operators Manual.

Note 1: New standard counts may be necessary more than once a day. See agency requirements.

Overview There are two methods for determining in-place density of soil / soil aggregate mixtures. See agency requirements for method selection.

Method A Single Direction

Method B Two Direction Procedure

1. Select a test location(s) randomly and in accordance with agency requirements. Test sites should be relatively smooth and flat and meet the following conditions:

a. At least 10 m (30 ft) away from other sources of radioactivity

b. At least 3 m (10 ft) away from large objects



c. The test site should be at least 150 mm (6 in.) away from any vertical projection, unless the gauge is corrected for trench wall effect.

2. Remove all loose and disturbed material, and remove additional material as necessary

to expose the top of the material to be tested.

3. Prepare a flat area sufficient in size to accommodate the gauge. Plane the area to a smooth condition so as to obtain maximum contact between the gauge and the material being tested. For Method B, the flat area must be sufficient to permit rotating the gauge 90 or 180 degrees about the source rod.

4. Fill in surface voids beneath the gauge with fines of the material being tested passing

the 4.75 mm (No. 4) sieve or finer. Smooth the surface with the guide plate or other suitable tool. The depth of the filler should not exceed approximately 3 mm (1/8 in.).

5. Make a hole perpendicular to the prepared surface using the guide plate and drive pin.

The hole shall be at least 50 mm (2 in.) deeper than the desired probe depth, and shall be aligned such that insertion of the probe will not cause the gauge to tilt from the plane of the prepared area. Remove the drive pin by pulling straight up and twisting the extraction tool.

6. Place the gauge on the prepared surface so the source rod can enter the hole without

disturbing loose material.

7. Insert the probe in the hole and lower the source rod to the desired test depth using the handle and trigger mechanism.

8. Seat the gauge firmly by partially rotating it back and forth about the source rod.

Ensure the gauge is seated flush against the surface by pressing down on the gauge corners, and making sure that the gauge does not rock.

9. Pull gently on the gauge to bring the side of the source rod nearest to the

scaler / detector firmly against the side of the hole.

10. Perform one of the following methods, per agency requirements:

a. Method A Single Direction: Take a test consisting of the average of two, one minute readings, and record both density and moisture data. The two wet density readings should be within 32 kg/m3 (2.0 lb/ft3) of each other. The average of the two wet densities and moisture contents will be used to compute dry density.

b. Method B Two Direction: Take a one-minute reading and record both density

and moisture data. Rotate the gauge 90 or 180 degrees, pivoting it around the source rod. Reseat the gauge by pulling gently on the gauge to bring the side of the source rod nearest to the scaler/detector firmly against the side of the



hole and take a one-minute reading. (In trench locations, rotate the gauge 180 degrees for the second test.) Some agencies require multiple one-minute readings in both directions. Analyze the density and moisture data. A valid test consists of wet density readings in both gauge positions that are within 50 kg/m3 (3.0 lb/ft3). If the tests do not agree within this limit, move to a new location. The average of the wet density and moisture contents will be used to compute dry density.

11. If required by the agency, obtain a representative sample of the material, 4 kg (9 lb)

minimum, from directly beneath the gauge full depth of material tested. This sample will be used to verify moisture content and / or identify the correct density standard. Immediately seal the material to prevent loss of moisture.

The material tested by direct transmission can be approximated by a cylinder of soil approximately 300 mm (12 in.) in diameter directly beneath the centerline of the radioactive source and detector. The height of the cylinder will be approximately the depth of measurement. When organic material or large aggregate is removed during this operation, disregard the test information and move to a new test site.

12. To verify the moisture content from the nuclear gauge, determine the moisture

content with a representative portion of the material using the FOP for AASHTO T 255/T 265 or other agency approved methods. If the moisture content from the nuclear gauge is within 1 percent, the nuclear gauge readings can be accepted. Retain the remainder of the sample at its original moisture content for a one-point compaction test under the FOP for AASHTO T 272, or for gradation, if required.

Note 2: Example: A gauge reading of 16.8 percent moisture and an oven dry of 17.7 percent are within the 1 percent requirements. Moisture correlation curves will be developed according to agency guidelines. These curves should be reviewed and possibly redeveloped every 90 days.

13. Determine the dry density by one of the following.

a. From nuclear gauge readings, compute by subtracting the mass (weight) of the water (kg/m3 or lb/ft3) from the wet density (kg/m3 or lb/ft3) or compute using the percent moisture by dividing wet density from the nuclear gauge by 1 + moisture content expressed as a decimal.

b. When verification is required and the nuclear gauge readings cannot be

accepted, the moisture content is determined by the FOP for AASHTO T 255/T 265 or other agency approved methods. Compute dry density by dividing wet density from the nuclear gauge by 1 + moisture content expressed as a decimal.

Percent Compaction Percent compaction is determined by comparing the in-place dry density as determined

by this procedure to the appropriate agency density standard. For soil or soil-aggregate mixes, these are moisture-density curves developed using the FOP for AASHTO



T 99/T 180. When using curves developed by the FOP for AASHTO T 99 / T 180, it may be necessary to use the FOP for AASHTO T 224 and FOP for AASHTO T 272 to determine maximum density and moisture determinations.

For coarse granular materials, the density standard may be density-gradation curves developed using a vibratory method such as AKDOT&PFs ATM 212, ITDs T 74, WSDOTs TM 606, or WFLHDs Humphrys.

See appropriate agency policies for use of density standards. Calculation

Wet density readings from gauge: 1963 kg/m3 (121.6 lb/ft3) 1993 kg/m3 (123.4 lb/ft3)

Avg: 1978 kg/m3 (122.5 lb/ft3)

Moisture readings from gauge: 14.2% and 15.4% = Avg 14.8%

Moisture content from the FOPs for AASHTO T 255/ T 265: 15.9% Moisture content is greater than 1 percent different so the gauge moisture cannot be used. Calculate the dry density as follows:

100 100

100 1

Where:

d = Dry density, kg/m3 (lb/ft3) w = Wet density, kg/m3 (lb/ft3) w = Moisture content from the FOPs for AASHTO T 255 / T 265, as a percentage

1978 122.5

15.9 100 100 1978 122.5

15.9100 1

Corrected for moisture Dry Density: 1707 kg/m3 (105.7 lb/ft3)



Calculate percent compaction as follows:

%Compaction 100 Report

Results on forms approved by the agency Location of test, elevation of surface, and thickness of layer tested. Visual description of material tested. Make, model and serial number of the nuclear moisture-density gauge. Wet density to 0.1 lb/ft3. Moisture content as a percent, by mass, of dry soil mass to 0.1 percent. Dry density to 0.1 lb/ft3. Standard density to 0.1 lb/ft3. Percent compaction. Name and signature of operator.



REVIEW QUESTIONS

1. Describe the calibration and standardization process.

2. What precautions must be taken in selecting a test location?

3. Describe the procedure leading up to the taking of test measurements.

4. What is the difference between Method A and Method B?

5. What is the purpose of determining moisture content by other means than the nuclear gauge?



REVIEW QUESTIONS

1. Describe the calibration and standardization process.

Calibrate the nuclear gauge, as required by the agency, every 12 months.

Standardize the nuclear gauge at the start of each day or when weather conditions change drastically. Warm gauge up for 10 20 minutes and then take standard count as per the manufacturers recommendation, and record both moisture and density in the Daily Standard Count Log.

2. What precautions must be taken in selecting a test location?

The test location shall be at least 30 ft. away from any other radioactive source,10 ft. away from any large object, and 6 inches away from any vertical projections.

3. Describe the procedure leading up to the taking of test measurements.

Remove all loose material from the test site. Prepare a flat area large enough to accommodate the test procedure to be used. Fill surface voids, up to 1/8 in depth. Using the guide plate, drive the pin perpendicular to the surface at least 2 deeper than the test to be taken. Remove pin without damaging the hole. Place gauge over hole and lower to desired test depth without deforming the sides of the hole. Pull the gauge back towards the operator until it is seated against the back side of the hole. Check the gauge for being level by putting hands on opposite corners of the gauge to see if it rocks or moves. Gauge is ready to start collecting test information.

4. What is the difference between Method A and Method B?

Method A: Gauge takes reading in one direction, minimum of 2, 1 minute counts, and the difference between the wet density readings should be within 2 lbs./ft.

Method B: Gauge takes reading in 2 directions, either 90 or 180 from the original reading, a minimum of 1, 1 minute reading in each direction, and the differences between the wet density readings should be within 3 lbs./ft.

5. What is the purpose of determining moisture content by other means than the nuclear gauge?

To ensure that the moisture content of the gauge is within 1% of these procedures due to moisture source decay.

COLORADO DEPARTMENT OF TRANSPORTATION

SOILS, EXCAVATION, & EMBANKMENT INSPECTION

March, 2015

Contents

Introduction ......................................................................................................................... 1

Chapter 1 - Road Construction Basics ................................................................................ 2

Chapter 2 - Preliminary Investigations ............................................................................... 4Geotechnical Explorations .............................................................................................. 4Borrow Sources ............................................................................................................... 6

Chapter 3 Basic Soil Mechanics ...................................................................................... 7Gradation Analyses ......................................................................................................... 7Atterberg Limits ............................................................................................................ 11AASHTO Soil Classification ........................................................................................ 12Soil Compaction ........................................................................................................... 14Generalized Soil Properties .......................................................................................... 16

Chapter 4: Roadway and Embankment Construction Methods ....................................... 18Foundation Preparation and Excavation ....................................................................... 18Embankment Fill ........................................................................................................... 19Placement and Lift Thickness Requirements ................................................................ 21Moisture Conditioning and Compaction Requirements ............................................... 22Grade Control and Proof Rolling .................................................................................. 25

Chapter 5 Common Soil Problems That Can Effect Construction ................................ 27Soft Clay Deposits Consolidation and Stability ........................................................ 27Swelling Soil and Heaving Bedrock ............................................................................. 30Collapsible Soils ........................................................................................................... 32Muck Excavation .......................................................................................................... 33Geosynthetics for Problem Soil Treatment ................................................................... 34

ii

Appendix 1: Determining the Liquid Limit of Soils FOP for AASHTO T89 Determining the Plastic Limit and Plasticity Index of Soils FOP for AASHTO T90

Appendix 2: AASHTO M-145 Soil Classification Example and Partial Group Index Determination

Appendix 3: Determination of Zero Air Voids Density of Soils with Varying Moisture Content and Specific Gravity

List of acronyms and abbreviations

American Association of State Highway and Transportation Officials AASHTO Colorado Department of Transportation CDOT Colorado Procedure CP Expanded Polystyrene Geofoam EPS Foam Mechanistic Empirical Pavement Design M-E Pavement

Design Liquid Limit LL Non Plastic NP No Value NV Optimum Moisture Content OMC Plasticity Index: PI Plastic Limit: PL Western Alliance for Quality Transportation Construction: WAQTC

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Introduction

Inspection and testing during embankment and roadway construction is one method that is used to improve the quality and performance of our highways. This process provides documentation that materials and construction procedures conform to project plans and specifications. The Colorado Department of Transportation (CDOT) certifies soils and embankment inspectors through the Western Alliance for Quality Transportation Construction (WAQTC). In addition to the WAQTC certification materials, CDOT desires to have our inspectors familiar with construction practices, geological conditions, testing procedures, and construction specifications that are unique for Colorado.

The goal of this manual is to help familiarize our inspectors with the equipment, testing, and construction practices utilized by CDOT for road and embankment construction. This manual provides background knowledge to help prepare our inspectors to perform their responsibilities during construction. The second portion of CDOTs soils and embankment certification process includes demonstrating a familiarity of the materials contained in this manual by passing a written exam with questions related to its content.

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Chapter 1 - Road Construction Basics

Constructing a roadway through a corridor typically requires alternating cut and fill sections to bring the roadway to the specified alignment and grade (Figures 1 and 2). Roadway designers make an attempt to balance cut and fill sections to avoid the need for importing embankment fill materials, and to avoid disposal of excess material after construction is completed.

Figure 1: Generalized embankment cross section.

Figure 2: Generalized roadway cut cross section.

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Roadway/Embankment Foundation The native materials onto which a road or embankment is constructed. These materials need to be adequately prepared to provide a stable foundation for the roadway and/or embankment. Preparation typically involves clearing and grubbing, followed by moisture conditioning and compaction. Preparation may also involve in-situ stabilization or even over-excavation and replacement if the materials consist of weak or poor quality soils.

Embankment Fill The materials used to raise grade to build the roadway up to a specified elevation and to provide support for the roadway and pavement section. Embankment fill material will vary from project to project based on geological conditions (i.e. the material that is locally available), project requirements, specifications, and cost.

Sub-Base A layer of aggregate material laid on the subgrade (or completed embankment), onto which the base course layer is placed.

Base Course A layer of clean sand and gravel that is designed as part of the pavement section to provide strength and increase the life span of the pavement. This layer also provides drainage and separation between the pavement and the underlying fill materials.

Side Slope The slope formed between the edges of the roadway shoulder and the toe of the embankment. The angle permitted for construction will vary depending on the materials used in the embankment, the quality of the foundation soils, quantity of fill materials available, and the height of the embankments on the project.

Cut Slope A designed slope that results from removing a high section of topography to accommodate the roadway alignment. The angle permitted for construction will vary depending on materials present within the cut section (i.e. stability), and the need to balance cut and fill quantities (cut slope angles may be increased/decreased to provide the required amount of fill materials for a project).

It is important for the inspector to become familiar with the structure of the roadway, the different soil types that are expected to be encountered in cut slopes and the foundations, and the types of soils that are specified for constructing the embankment and pavement section. Changed conditions or a change in expected materials may require modification of the construction requirements to improve the quality of the finished roadway.

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Chapter 2 - Preliminary Investigations

Before roadway or embankment construction even begins, designers and engineers need to become familiar with the types of soils and bedrock that will be encountered on a project. An understanding of groundwater conditions is also necessary. It is necessary to understand foundation conditions for the roadway and embankments, to characterize the materials in cut sections, and to characterize materials in potential borrow source areas. A subsurface investigation is conducted prior to design of any road construction project to gain an understanding of the geological conditions present, and to identify the materials available for construction. These investigations assist engineers in designing embankments and roadways to perform adequately with the materials available and the ground conditions present.

Geotechnical Explorations

General guidelines for geotechnical explorations are presented in Chapter 4 of the 2015 Colorado Mechanistic Empirical (M-E) Pavement Design Manual and Chapter 200 of the 2015 CDOT Field Materials Manual: Soil Survey/Preliminary Soil Profile. These manuals provide information on several methods used to characterize the subsurface conditions within a project site or alignment and provide guidelines for collection of soil and bedrock samples for testing and classification. Geotechnical explorations can include drilling soil borings into the subsurface, excavating test pits, and/or the use of geophysical methods to characterize the subsurface conditions. The primary purpose of conducting geotechnical explorations is to identify, delineate, and classify various geological units and soil types through a corridor, and to collect soil samples for laboratory testing.

Photograph 1: Subsurface explorations and soil sampling being conducted with a drill rig.

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With this information designers can determine which materials are/are not suitable for use as construction materials, what areas are suitable to build roadways and embankments on, and what areas will require special treatment and stabilization during construction. This information is then conveyed to contractors through the Plans and Specifications that are developed for a project. CDOT soil inspectors need to become familiar with the unique earthwork requirements specified for their given projects.

Chapter 4 of the 2015 Colorado M-E Pavement Design Manual and Chapter 200 of the 2015 CDOT Field Materials Manual also provide general guidelines for the minimum recommended spacing and depth of geotechnical explorations. For new roadway and embankment construction projects, the following recommendations are given:

Test holes should not be spaced more than 1,000 feet apart along a corridor alignment through at-grade or fill sections. In continuous cut sections, test holes should not be spaced more than 500 feet apart (Figure 3).

Subsurface characterization of the upper 5 to 8 feet of the subgrade is required for the M-E Pavement Design Methodology (cuts and at-grade sections). Therefore, it is recommended that borings extend a minimum of 5 to 8 feet below the final proposed grade (Figure 3). It is also recommended that occasional borings extend to the water table or at least to 10 feet in depth to characterize deeper materials below the planned subgrade elevation.

For embankments higher than 20 feet, test holes should extend a minimum of 5 feet into bedrock or similar hard stratum (Figure 3).

Test holes should extend through the highest portion of a cut section and extend to a minimum depth of 5 to 8 feet below the proposed finished grade (Figure 3).

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Figure 3: Generalized roadway profile illustrating minimum required geotechnical test hole spacing and depth requirements.

In addition to these requirements, it is recommended that additional explorations be conducted to capture known changes in geological conditions within a corridor. Some projects may require more extensive investigations; in particular high-speed multi-lane facilities in rough terrain or through areas with complex geological conditions.

Borrow Sources

Another purpose of conducting preliminary geotechnical explorations is to identify potential borrow sources for materials that can be used for new highway construction. Borrow pits are permitted areas where approved material is excavated or acquired from stockpiles. If CDOT has the permits to a borrow pit and offers the pit to a contractor it is designated an available source. Any borrow sources other than an available source is considered a contractor source, and it is the contractors responsibility to obtain any necessary permits and certify that no hazardous materials exist in the source.

Geotechnical explorations are required to identify, sample, and classify potential borrow source areas. Representative soil samples must be submitted to a Region/Central lab for classification and testing before being approved for use in embankment construction. A pit sketch and sampling request must be submitted to the Region Materials Engineer for approval.

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Chapter 3 Basic Soil Mechanics

Soil and embankment inspectors need to understand basic information about soils, testing procedures to classify soils, and how different soil types behave when they are used as an engineered material (i.e compaction, drainage, stability, etc.). This chapter provides a summary of basic soil mechanics and laboratory testing procedures used to determine soil index and engineering properties.

The American Association of State Highway and Transportation Officials (AASHTO) has developed a system for classifying soils into groups based on their different index properties. This classification system is referred to as AASHTO M-145, and is described below. The classification system is based on a soils grain size distribution and Atterberg limits. These index properties, the tests used determine them, and a summary of the classification system are also described below.

Gradation Analyses

A gradation analysis is a method used to quantitatively determine the distribution of particle sizes in soils, aggregate, or soil-aggregate mixtures. Colorado Procedure (CP) 21, Mechanical Analysis of Soils, describes the procedure to run this test. An oven-dried soil sample that consists of a variety of particle sizes is passed through a series of sieves with different sized openings. The material that is collected or retained on each sieve is then weighed, and the percent mass of each particle size for the soil sample is calculated, then plotted on a grain size curve. The various sieve sizes that are used to classify the grain size distribution of a soil are included in Tables 1 and 2 below. This test is also referred to as a grain size analysis, particle size analysis, or sieve analysis. An example grain size curve is provided in Figure 4.

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Table 1: Standard Sieve Sizes Used for Gradation Analyses (ASTM Classification)

Sieve Size/Number Number of Openings per Square Inch

Soil Type

3-inch --

Gravel

1- -inch --

-inch --

-inch -- # 4 4

# 10 10

Course Sand # 20 20

# 40 40

# 50 50

Fine Sand # 100 100

# 200 200

< # 200 -- Fines (Silt and Clay)

Notes: Cobbles are defined as particle sizes between 3 inches and 12 inches in diameter. Boulders are defined as particle sizes larger than 12 inches in diameter.

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Table 2: Standard Sieve Sizes Used for Gradation Analyses (AASHTO Classification)

Sieve Size/Number Number of Openings per Square Inch

Soil Type

3-inch --

Gravel

1-inch --

-inch --

-inch -- # 4 4

# 10 10

# 40 40 Coarse Sand

# 200 200 Fine Sand

< # 200 -- Fines (Silt and Clay)

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Figure 4: Example grain size curve (ASTM Classification).

A sufficient amount of soil needs to be sampled to run a representative gradation test. The minimum mass of material required is dependent on the Nominal Maximum Size of aggregate or particle in the sample. The Nominal Maximum Size is defined as the smallest sieve opening through which the entire amount of specimen passes. For example, if 100 percent of a specimen passes the 1- -inch sieve, and material begins to collect on the next smallest sieve, the nominal maximum size of the sample is 1- -inch. Table 3 below summarizes the minimum test sample masses that are required for a gradation test given various nominal maximum particle sizes.

0.010.1110100Diameter (mm)

SIEVE ANALYSIS AASHTO T 27

Percent P

assing

NO. 200NO. 100NO. 50NO. 40NO. 20NO. 10NO. 43/8"1 1/2"3"

SIEVE ANAYLSIS

U.S. Standard Sieves

Hydrometer Analysis

Time Readings3/4"

% Gravel: 28.7 % Course Sand: 25.5 % Fines (Silt and Clay): 36.3 % Fine Sand: 9.5

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Table 3: Required Test Sample Masses for Gradation Analyses of Aggregate Given Various Nominal Maximum Particle Sizes

Nominal Maximum

Size of Aggregate

CDOT Required Minimum Test Sample Masses

Pounds Grams

3- -inch 33.0 15,000

3 -inch 27.5 12,500

2- -inch 22.0 10,000

2 -inch 16.5 7,500

1- -inch 11.0 5,000

1 -inch 5.5 2,500

-inch 4.4 2,000

-inch 3.3 1,500

-inch 2.2 1,000 < -inch 0.66 300

Note: All test sample masses are dry masses.

Atterberg Limits

The Atterberg limits define the range of moisture contents in which a soil behaves as a plastic. As the moisture content of a clayey soil increases, the material behavior will change from a solid, to a semi-solid, to plastic, and eventually to a liquid (Figure 5). The specific moisture contents that need to be determined for AASHTO M-145 soil classification are the plastic limit (PL) and the liquid limit (LL). The plastic limit of a soil is the lowest water content at which the soil remains plastic. The liquid limit is the moisture content at which the soil behavior changes from a plastic to a liquid state. The range of moisture contents that a soil behaves as a plastic is referred to as the plasticity index (PI), and is taken as the

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